Magnitudes of muscle activation of spine stabilizers in healthy adults during prone on elbow planking exercises with and without a fitness ball

Prone planking exercises have been used by rehabilitation professionals to activate torso muscles in healthy persons and those with low back pain. The aim of this study was to compare the magnitude of electromyographic (EMG) muscle activation from 10 right-sided muscles as demonstrated by the percentage of maximum voluntary isometric contraction (%MVIC) during four planking procedures. Surface EMG activity was acquired from the following muscles: (1) iliocostalis lumborum (IL), (2) longissimus thoracis (LT), (3) lumbar multifidus (LM), (4) rectus abdominis (RA), (5) external oblique (EO), (6) internal oblique (IO), (7) serratus anterior (SA), (8) latissimus dorsi (LD), (9) hamstrings (HS), and (10) gluteus maximus (GM). Thirteen male and 13 females performed prone plank on floor (PPOF), prone plank on ball (PPOB), stir-the-pot on ball (STP), and prone plank on ball with hip extension (PPHE). Previous investigators have not studied the STP and PPHE. During STP, three muscles (RA, EO, and IO) demonstrated very high (>61% MVIC) EMG activation and one muscle (SA) demonstrated high (41–60% MVIC) EMG activation. During PPHE, five muscles (GM, HS, EO, IO, and LM) demonstrated very high EMG activation and two muscles (RA and SA) demonstrated high EMG activation. Clinically, we concluded that STP and PPHE exercises were effective ways to activate RA, EO, IO, and SA at levels conducive to strengthening (> 50% MVIC), with PPHE able to additionally activate GM, HS, and LM at a strengthening level.     

Electromyographic activity of the hip and knee muscles during functional tasks in males with and without patellofemoral pain

Background

Patellofemoral pain (PFP) is a common overuse injury in physically active individuals. It is characterized by anterior knee, retropatellar, or prepatellar pain associated with activities that increase patellofemoral joint stress such as squatting, stair ascending and descending, running, jumping, prolonged sitting, and kneeling. The etiology of PFP is believed to be multifactorial. Recently, proximal factors have been shown to influence the biomechanics of patellofemoral joint.

咀嚼肌功能训练辅助矫治开[牙合]患者的效果观察

目的探讨咀嚼肌功能训练辅助矫治开殆患者的效果。方法对18例开[牙合]合患者在肌训练前及训练3个月后进行肌电检查,评价训练前后咀嚼肌肌电活动的变化情况。结果训练前后两组肌电变化比较差异有显著意义,训练后肌电活动均高于训练前（P〈0．05,P〈0．01）。结论肌训练有效提高了咬肌收缩,改善了咀嚼功能,对开[牙合]患者的矫治效果有利,疗效确切,值得推广。     

Performance,reliability and fatigue in prone bridge test and supine unilateral bridge test

IntroductionThe core muscles can be evaluated through functional tests, such as the prone bridge test (PBT) and supine unilateral bridge test (SUBT). However, there are differences in reliability and muscle fatigue related to these tests.MethodsThe study evaluated 30 sedentary individuals and 30 individuals who practiced resistance exercises. Participants performed the PBT and SUBT in association with muscle recruitment, through surface electromyography of the upper and lower limbs and trunk muscles. The order of the tests was random and the participants performed one repetition of each test until fatigue. After a 30-min rest interval the participants repeated the tests. After one week, the participants returned and repeated the tests.ResultsThe resistance group (RG) presented longer PBT holding time (RG 111.8 ± 9.4 and sedentary group (SG) 81 ± 7.7; p = 0.01), while the holding time in the SUBT was similar for both groups (RG = 100.7 ± 8.1 and SG = 79 ± 9.2; p = 0.09). Good to excellent reliability (ICC >0.836; SEM < 3.85) was established for the PBT and SUBT. Comparing the two groups there were no significant differences or interactions regarding muscle fatigue. The intragroup analysis on the PBT indicated greater gluteus maximus muscle fatigue, and for the SUBT the rectus abdominis presented greater fatigue, in both groups.ConclusionThe PBT and SUBT are reliable. Resistance exercise practitioners maintain the PBT for a longer time. The PBT led to greater gluteus maximus muscle fatigue, while the SUBT generated greater fatigue in the rectus abdominis and gluteus medius, in both groups.     

Comparison between the Ki-hap technique and verbal encouragement on activation of abdominal muscles in healthy participants

The aim of this study was to investigate the comparison between a Ki-hap, defined as a psyching-up technique, and verbal encouragement, defined as a verbal command by a third party, on abdominal muscle activation during performance of the crunch exercise in healthy participants. Ninety participants were randomly allocated to the following three groups: crunch only exercise group (CG, n₁ = 30), crunch exercise with Ki-hap group (CKG, n₂ = 30), and crunch exercise with Ki-hap and verbal encouragement group (CKVG, n₃ = 30). The interventions were conducted over three trials with each group, and measurements involving each participant, were performed by a single examiner. The activation of the rectus abdominis (RA), external oblique (EO), and internal oblique (IO) muscles were evaluated using electromyography (EMG) during performance of the crunch exercise by the CG, CKG, and CKVG. Our results showed a significantly greater increase in the EMG patterns of all muscles during performance of the crunch exercise in the CKG (p < 0.05) compared to those in the CG and CKVG. The results also showed that there was a significantly greater increase in the activation of the EO and IO muscles in the CKVG (p < 0.05) compared with that in the CG. These findings demonstrated that the addition of the Ki-hap technique and verbal encouragement, during performance of the crunch exercise, improves activation of the abdominal muscles.     

HIP MUSCLE ACTIVATION AND KNEE FRONTAL PLANE MOTION DURING WEIGHT BEARING THERAPEUTIC EXERCISES

Purpose/Background:

Hip abduction strengthening exercises may be critical in the prevention and rehabilitation of both overuse and traumatic injuries where knee frontal plane alignment is considered to be important. The purpose of the current investigation was to examine the muscular activation of the gluteus maximus and gluteus medius during the double-leg squat (DLS), single-leg squat (SLS), or front step-up (FSU), and the same exercises when an added load was used to pull the knee medially.

Methods:

Eighteen healthy females (ages 18-26) performed six exercises: DLS, DLS with load, FSU, FSU with load, SLS, and SLS with load. Integrated and peak surface electromyography of gluteus maximus and gluteus medius of the dominant leg were recorded and normalized. Motion analysis was used to measure knee abduction angle during each exercise.

Results:

SLS had the highest integrated and peak activation for both muscles, regardless of load. Adding load, only increased DLS integrated gluteus maximus activation (p=0.019). Load did not increase integrated gluteus medius or peak gluteus maximus activation. Adding load decreased SLS peak gluteus medius activation (p=0.003). Adding load increased peak knee abduction angle during DLS (p=0.013), FSU (p=0.000), and SLS (p=0.011).

Conclusions:

Overall, the SLS was most effective exercise for activating the gluteus maximus and gluteus medius. Applied knee load does not appear to increase muscle activation during SLS and FSU. DLS with an applied load may be more beneficial in activating the gluteus maximus. Overall, the use of applied loads appears to promote poorer musculoskeletal alignment in terms of peak knee valgus angle.Level of Evidence: 3     

Acute effects of different rest intervals between agonist-antagonist paired-sets in the neuromuscular system performance of young adults

IntroductionThe agonist-antagonist paired-sets (APS) is a resistance training that involves alternating between exercises for agonist/antagonist muscles of a joint, with little or no rest between then. There is evidence that APS is more strenuous than traditional methods, but evidence on the optimal RI between agonist-antagonist actions is unknown.ObjectiveThe aim of this study was to compare different rest intervals between agonist-antagonist actions during APS in young adults.MethodFifty healthy men (mean age 23.2 ± 2.8 years; 1.76 ± 0.1m height, 78.03 ± 8.1 kg) were included and performed three different agonist-antagonist paired-sets protocols separated by 72h, consisting of 4 sets of 10 repetitions. The protocols differed in terms of the rest interval between the knee flexion and extension movements: 0s (no rest); 60s and 120s. The rest intervals between exercise sets were standardized at 60s. Total work, peak torque, neuromuscular efficiency, surface EMG amplitude (sEMG, root mean square) and fatigue index obtained by processing of sEMG signal, were compared between rest intervals and exercise sets within each protocol.ResultsThere were no significant differences between rest intervals for total work, peak torque and neuromuscular efficiency (P > 0.05), but significant differences were found for sEMG and fatigue (P < 0.01), in which the protocol with 60s interval resulted in greater fatigue.ConclusionWe showed that peak torque, total work and neuromuscular efficiency were not different between RI. The 60s RI showed a lower sEMG and a greater muscle fatigue. Although there were no significant differences, the NME was higher in the 60s interval.     

Neck flexor muscle fatigue in adolescents with headache: an electromyographic study.

BACKGROUND: Muscular disorders of the neck region may be of importance for the etiology of tension-type headache. However, in adolescents, there are no data on the association between neck muscle fatigue and headache. AIM: To study differences in fatigue characteristics of the neck flexor muscles in adolescents with and without headache. METHODS: A population-based sample of 17-year-old adolescents with migraine-type headache (N=30), tension-type headache (N=29) and healthy controls without headache (N=30) was examined. Surface EMG data were recorded from the sternocleidomastoid (SCM) muscles bilaterally during an isometric neck flexor endurance test. The spectral median frequency (MF) change during the total endurance time (TMF) and the initial time of 30s (IMF) was calculated. The intensity of discomfort in the neck area was assessed with the visual analogue scale (VAS). RESULTS: The rate of decline in TMF of both SCM muscles was significantly increased in the tension-type headache group compared with controls (right SCM, P=0.030, OR 2.0, 95% 1.2-3.7; left SCM, P=0.009, OR 2.5, 95% 1.4-4.9), while no significant differences were found between controls and subjects with migraine. The rate of decline in IMF, the total endurance time (P=0.050), and VAS did not differ significantly among the study groups. CONCLUSIONS: This preliminary finding shows that increased neck flexor muscle fatigue in adolescents seems to be associated with tension-type headache.     

The effect of delayed onset of muscle soreness on habitual trapezius activity

The aim of the study was to investigate the effect of acute trapezius pain, induced by delayed onset of muscle soreness (DOMS), on habitual trapezius activity. Long‐term (5 h) surface electromyographic (sEMG) activity was recorded bilaterally from the clavicular, descending, transverse, and ascending trapezius on two consecutive weekdays in eleven female subjects (mean age 22 years, range 20–24 years). Body and arm posture were recorded by inclinometers. Immediately after the first long‐term recording, the subjects performed eccentric depression exercise of the left shoulder to induce DOMS. From day 1 to day 2, pressure pain threshold (PPT) decreased and pain scores on visual analog scale (VAS) increased for the left upper trapezius (P <.004 for all comparisons). Habitual sEMG activity (median sEMG level, μV) of the clavicular and descending part of the exercised left trapezius increased from first to second long‐term recording during periods with seated posture (P <.05 for both comparisons). In contrast, trapezius sEMG activity remained unchanged for all other trapezius parts and postures. This study indicates that acute trapezius pain induces elevated habitual trapezius activity during periods with low biomechanical loading of the shoulder/neck muscles with the elevated sEMG activity being restricted to the painful part of the muscle. In contrast to the pain‐adaption model, the current study indicates a relation between acute muscle pain and elevated low‐level muscle activity; however, it remains unknown if development of chronic muscle pain can be preceded by an initial stage with elevated muscle activity.     

Surface electromyographic activity of five residual limb muscles recorded during isometric contraction in transfemoral amputees with osseointegrated prostheses

Background

Femoral osseointegrated implants represent a new development in amputee rehabilitation, eliminating socket pressure discomfort, improving hip range of movement and facilitating prosthetic limb attachment. A clinical aspect that has not previously been reported on is the function of muscles in the residuum with implications concerning energy expenditure, hip-hiking and viability of the electrogram as a myoprocessor. Typically, amputees fitted with osseointegrated fixation have shorter residuums and weaker attachment of cleaved muscles. Function of muscle can be assessed by surface electromyography through changes in amplitude and median frequency of the signal.

Methods

Five male transfemoral amputees with osseointegrated fixations participated together with a control group comprised of ten adult males. Electrodes recorded surface electromyographic activity of five residual limb muscles or left lower limb muscles of control subjects. Isometric contractions were performed against resistance. The increase in mean rectified amplitude from resting to maximally contracting was calculated and median frequencies estimated.

Findings

The amputees were unable to maintain a maximum voluntary contraction of constant amplitude. Amplitude increase was lowest for rectus femoris and adductor magnus. The median frequency of adductor magnus was significantly greater (P = 0.02) for the amputees than intact subjects and there was a significant difference (P < 0.01) between gluteus maximus and adductor magnus for amputee subjects.

Interpretation

High electromyographic amplitude variability suggests that using residuum muscles singly as a myoprocessor might be challenging. Adductor magnus displayed a different sEMG profile compared to intact subjects indicating decreased function and neuromuscular changes. Further work into optimal muscle anchorage is required to ensure maximal mechanical performance.     

Manuscript Reviewers

Abstract

Aim: To investigate the pattern of overflow facilitated by the use of resistive proprioceptive neuromuscular facilitation (PNF). Method: In a group of 12 young, healthy individuals, recruitment of electrical activity into the tibialis anterior (TA) muscle of the right lower limb (RLL) was assessed using surface electromyography (sEMG) during a random-sequence application of manually-resistive PNF to the other three limbs. Results: Resistance exercise applied to the left lower limb (LLL) was associated with a considerable increase in sEMG activity in the RLL TA muscle compared to its baseline level (p?=?0.001). Resistance exercise applied to the right or left upper limbs (RUL or LUL) respectively showed similar sEMG activity in RLL TA muscle to its baseline level. Conclusion: A resistance exercise would appear to be effective in producing electrical activity in the contralateral homologous muscles of non-exercised limb.     

Effect of stretch positions on hamstring muscle length,lumbar flexion range of motion,and lumbar curvature in healthy adults

Hamstring stretching is a common practice in physical therapy to change not only hamstring muscle length (HML), but also lumbar flexion range of motion (LROM) or lumbar curvature (LC). Yet limited published research compares the effectiveness of two commonly used hamstring stretch positions, sitting and standing. The purposes of this study were to determine the effect of (1) stretch position on HML; and 2) HML on LROM and LC. Thirty-six participants (M=44.8 years, SD=17.1) with short HML (i.e., with shortness for men ≥45° and for women ≥24° of active knee flexion with 90° hip flexion) were measured for HML, LROM, and LC; randomly allocated to one of three groups: (1) hamstring stretching in sitting (SI); (2) standing (ST); or (3) no stretching (control); and remeasured after 4 weeks. Participants in the stretching groups performed two 30-second static stretches 4 days per week for 4 weeks. Multivariate analysis of covariance (MANCOVA) showed significance between the stretching groups and nonstretching group for HML only. Nonsignificance was shown for HML between the stretch positions (i.e., SI–active knee extension (AKE) and ST-AKE), indicating that both were equally effective for increasing HML. However, there was no change in LROM or in LC even though HML increased.     

Creation of an asymmetrical gradient of back muscle activity and spinal stiffness during asymmetrical hip extension

Background

Low back pain is often associated with increased spinal stiffness which thought to arise from increased muscle activity. Unfortunately, the association between paraspinal muscle activity and paraspinal stiffness, as well as the spatial distribution of this relation, is unknown. The purpose of this investigation was to employ new technological developments to determine the relation between spinal muscle contraction and spinal stiffness over a large region of the lumbar spine.

Methods

Thirty-two male subjects performed graded isometric prone right hip extension at four different exertion levels (0%, 10%, 25% and 50% of the maximum voluntary contraction) to induce asymmetric back muscle activity. The corresponding stiffness and muscle activity over bilateral paraspinal lumbar regions was measured by indentation loading and topography surface electromyography, respectively. Paraspinal stiffness and muscle activity were then plotted and their correlation was determined.

Findings

Data from this study demonstrated the existence of an asymmetrical gradient in muscle activation and paraspinal stiffness in the lumbar spine during isometric prone right hip extension. The magnitude and scale of the gradient increased with the contraction force. A positive correlation between paraspinal stiffness and paraspinal muscle activity existed irrespective of the hip extension effort (Pearson correlation coefficient, range 0.566–0.782 (P < 0.001)).

Interpretation

Our results demonstrate the creation of an asymmetrical gradient of muscle activity and paraspinal stiffness during right hip extension. Future studies will determine if alterations in this gradient may possess diagnostic or prognostic value for patients with low back pain.     

The vastus medialis oblique:vastus lateralis electromyographic intensity ratio does not differ by gender in young participants without knee pathology

Objectives

To investigate whether there was a gender difference in the intensity of electromyographic (EMG) activity in vastus medialis oblique (VMO) relative to vastus lateralis (VL).

Design

A cross-sectional observational study measuring EMG activity during stepping down from a step and during straight leg raise exercises.

Setting

University campus laboratory.

Participants

Two groups of healthy participants were tested, one female (mean age 23.5 years, n = 15) and one male (mean age 23.5 years, n = 15).

Main outcome measures

Surface EMG activity (sampling rate 1000 Hz) was recorded from VMO and VL of the dominant limb during five repetitions of a step down activity and five repetitions of a straight leg raise exercise. The average intensity of the rectified and smoothed EMG activity from each activity was normalised to that elicited in a maximal quadriceps setting exercise. The ratio of normalised VMO:VL EMG intensity levels was calculated.

Results

The median difference in the VMO:VL ratio between the groups was 0.11 [approximate 95% confidence interval (CI) −0.62 to 1.00] during step down and −0.07 (approximate 95% CI −0.26 to 0.20) during straight leg raise. Using Mann Whitney U-tests, these differences were not statistically significant (P = 0.648 and 0.619, respectively).

Conclusions

This study found no gender difference in the VMO:VL EMG intensity ratio in asymptomatic participants. This suggests that the difference in incidence of patellofemoral pain syndrome between genders is not influenced by quadriceps intensity ratios, when participants are asymptomatic.     

Surface electromyography activity of upper limb muscle during wheelchair propulsion: Influence of wheelchair configuration

Background

Biomechanical studies have linked handrim wheelchair propulsion with a prevalence of upper limb musculoskeletal disorders. The purpose of this study was to record upper limb muscle recruitment patterns using surface electromyography during wheelchair propulsion. Recordings were made for various wheelchair configurations to understand the effect of wheelchair configuration on muscle recruitment.

Methods

Ten paraplegic and ten able-bodied subjects propelled a test wheelchair on a roller ergometer system at a comfortable speed. Twelve wheelchair configurations were tested. Upper limb surface electromyography and kinematics were recorded for each configuration. Based on the hand position relative to the handrim, the propulsion cycle was divided into three phases to explain the activation patterns.

Findings

Compared to the able-bodied subjects, the paraplegic subjects presented higher activation. This is the case for all muscles in the early push phase, for the triceps brachii, pectoralis major and latissimus dorsi in the late push phase and for the trapezius, triceps brachii and latissimus dorsi during recovery. During early push, activation of nearly all muscles was affected by the axle position, where as seat height only affected biceps brachii and pectoralis major activation. During late push, the deltoid anterior was affected by axle position and the biceps brachii by seat height. During recovery, the trapezius was affected by axle position, the deltoid posterior by seat height and the biceps brachii by both.

Interpretation

Upper limb muscle recruitment differences highlight that future studies on wheelchair propulsion should only be done with wheelchair experienced paraplegic subjects. Furthermore, this study provides indications on how muscle recruitment is affected by wheelchair configuration.     

ELECTROMYOGRAPHIC ANALYSIS OF GLUTEUS MEDIUS AND GLUTEUS MAXIMUS DURING REHABILITATION EXERCISES

Purpose/Background:

Previous research studies by Bolga, Ayotte, and Distefano have examined the level of muscle recruitment of the gluteal muscles for various clinical exercises; however, there has been no cross comparison among the top exercises from each study. The purpose of this study is to compare top exercises from these studies as well as several other commonly performed clinical exercises to determine which exercises recruit the gluteal muscles, specifically the gluteus medius and maximus, most effectively.

Methods:

Twenty-six healthy subjects participated in this study. Surface EMG electrodes were placed on gluteus medius and maximus to measure muscle activity during 18 exercises. Maximal voluntary muscle contraction (MVIC) was established for each muscle group in order to express each exercise as a percentage of MVIC and allow standardized comparison across subjects. EMG data were analyzed using a root-mean-square algorithm and smoothed with a 50 millisecond time reference. Rank ordering of the exercises was performed utilizing the average percent MVIC peak activity for each exercise.

Results:

Twenty-four subjects satisfied all eligibility criteria and consented to participate in the research study. Five of the exercises produced greater than 70%MVIC of the gluteus medius muscle. In rank order from highest EMG value to lowest, these exercises were: side plank abduction with dominant leg on bottom (103%MVIC), side plank abduction with dominant leg on top (89%MVIC), single limb squat (82%MVIC), clamshell (hip clam) progression 4 (77%MVIC), and font plank with hip extension (75%MVIC). Five of the exercises recruited gluteus maximus with values greater than 70%MVIC. In rank order from highest EMG value to lowest, these exercises were: front plank with hip extension (106%MVIC), gluteal squeeze (81%MVIC), side plank abduction with dominant leg on top (73%MVIC), side plank abduction with dominant leg on bottom (71%MVIC), and single limb squat (71%MVIC). Four of the exercises produced greater than 70%MVIC for both gluteus maximus and medius muscles.

Conclusions:

Higher %MVIC values achieved during performance of exercises correlate to muscle hypertrophy.^20,22 By knowing the %MVIC of the gluteal musculature that occurs during various exercises, potential for strengthening of the gluteal muscles can be inferred. Additionally, exercises may be rank ordered to appropriately challenge the gluteal musculature during rehabilitation.     

Diagnosing and treating neurogenic orthostatic hypotension in primary care

In response to a change in posture from supine or sitting to standing, autonomic reflexes normally maintain blood pressure (BP) by selective increases in arteriovenous resistance and by increased cardiac output, ensuring continued perfusion of the central nervous system. In neurogenic orthostatic hypotension (NOH), inadequate vasoconstriction and cardiac output cause BP to drop excessively, resulting in inadequate perfusion, with predictable symptoms such as dizziness, lightheadedness and falls. The condition may represent a central failure of baroreceptor signals to modulate cardiovascular function, a peripheral failure of norepinephrine release from cardiovascular sympathetic nerve endings, or both. Symptomatic patients may benefit from both non-pharmacologic and pharmacologic interventions. Among the latter, two pressor agents have been approved by the US Food and Drug Administration: the sympathomimetic prodrug midodrine, approved in 1996 for symptomatic orthostatic hypotension, and the norepinephrine prodrug droxidopa, approved in 2014, which is indicated for the treatment of symptomatic neurogenic orthostatic hypotension caused by primary autonomic failure (Parkinson’s disease, multiple system atrophy and pure autonomic failure). A wide variety of off-label options also have been described (e.g. the synthetic mineralocorticoid fludrocortisone). Because pressor agents may promote supine hypertension, NOH management requires monitoring of supine BP and also lifestyle measures to minimize supine BP increases (e.g. head-of-bed elevation). However, NOH has been associated with cognitive impairment and increases a patient’s risk of syncope and falls, with the potential for serious consequences. Hence, concerns about supine hypertension – for which the long-term prognosis in patients with NOH is yet to be established – must sometimes be balanced by the need to address a patient’s immediate risks.     

Polar-phase indices of perioral muscle reciprocity during syllable production in Parkinson’s disease

Purpose: This research characterised perioral muscle reciprocity and amplitude ratio in lower lip during bilabial syllable production [pa] at three rates to understand the neuromotor dynamics and scaling of motor speech patterns in individuals with Parkinson’s disease (PD).

Method: Electromyographic (EMG) signals of the orbicularis oris superior [OOS], orbicularis oris inferior [OOI] and depressor labii inferioris [DLI] were recorded during syllable production and expressed as polar-phase notations.

Result: PD participants exhibited the general features of reciprocity between OOS, OOI and DLI muscles as reflected in the EMG during syllable production. The control group showed significantly higher integrated EMG amplitude ratio in the DLI:OOS muscle pairs than PD participants. No speech rate effects were found in EMG muscle reciprocity and amplitude magnitude across all muscle pairs.

Conclusion: Similar patterns of muscle reciprocity in PD and controls suggest that corticomotoneuronal output to the facial nucleus and respective perioral muscles is relatively well-preserved in our cohort of mild idiopathic PD participants. Reduction of EMG amplitude ratio among PD participants is consistent with the putative reduction in the thalamocortical activation characteristic of this disease which limits motor cortex drive from generating appropriate commands which contributes to bradykinesia and hypokinesia of the orofacial mechanism.